Light Absorbers and Catalysts for Solar to Fuel Conversion By Nikolay I Kornienko A dissertation ...

112 Pages·2016·6.72 MB·English

Light Absorbers and Catalysts for Solar to Fuel Conversion

By
Nikolay I Kornienko

A dissertation submitted in satisfaction of the requirements for the degree of
Doctor of Philosophy
In
Chemistry
in the
Graduate Division
of the
University of California, Berkeley

Committee in charge:

Professor Peidong Yang, Chair
Professor Gabor Somorjai
Professor Junqiao Wu
Professor Tanja Cuk

Spring 2016

Abstract
Light Absorbers and Electrocatalysts for Solar to Fuel Conversion
by
Nikolay I Kornienko
Doctor of Philosophy in Chemistry
University of California, Berkeley
Professor Peidong Yang, Chair

Increasing fossil fuel consumption and the resulting consequences to the environment has
propelled research into means of utilizing alternative, clean energy sources. Solar power is
among the most promising of renewable energy sources but must be converted into an energy
dense medium such as chemical bonds to render it useful for transport and energy storage.
Photoelectrochemistry (PEC), the splitting of water into oxygen and hydrogen fuel or reducing
CO to hydrocarbon fuels via sunlight is a promising approach towards this goal.
2
Photoelectrochemical systems are comprised of several components, including light
absorbers and catalysts. These parts must all synergistically function in a working device.
Therefore, the continual development of each component is crucial for the overall goal. For PEC
systems to be practical for large scale use, the must be efficient, stable, and composed of cost
effective components. To this end, my work focused on the development of light absorbing and
catalyst components of PEC solar to fuel converting systems.
In the direction of light absorbers, I focused of utilizing Indium Phosphide (InP)
nanowires (NWs) as photocathodes. I first developed synthetic techniques for InP NW solution
phase and vapor phase growth. Next, I developed light absorbing photocathodes from my InP
NWs towards PEC water splitting cells.
I studied cobalt sulfide (CoSx) as an earth abundant catalyst for the reductive hydrogen
evolution half reaction. Using in situ spectroscopic techniques, I elucidated the active structure
of this catalyst and offered clues to its high activity.
In addition to hydrogen evolution catalysts, I established a new generation of earth
abundant catalysts for CO reduction to CO fuel/chemical feedstock. I first worked with
2
molecularly tunable homogeneous catalysts that exhibited high selectivity for CO reduction in
2
non-aqueous media. Next, in order to retain molecular tunability while achieving stability and
efficiency in aqueous solvents, I aimed to heterogenize a class of molecular porphyrin catalysts
into a 3D mesoscopic porous catalytic structure in the form of a metal-organic framework
(MOF).To do so, I initially developed a growth for thin film MOFs that were embedded with
catalytic groups in their linkers.6 Next, I utilized these thin film MOFs grown on conductive
substrates and functionalized with cobalt porphyrin units as 3D porous CO reduction catalysts.
2
This new class of catalyst exhibited high efficiency, selectivity, and stability in neutral pH
aqueous electrolytes.
1
Finally, as a last chapter of my work, I explored hybrid inorganic/biological CO
2
reduction pathways. Specifically, I used time-resolved spectroscopic and biochemical techniques
to investigate charge transfer pathways from light absorber to CO -derived acetate in acetogenic
2
self-sensitized bacteria.
2
Table of Contents:

1. Publication List ii
2. Intriduction: 1
3. InGaP Solution Phase Synthesis and Photocathode Development: 3
4. InP Vapor Phase Synthesis and Photocathode Development: 17
5. Cobalt Sulfide Hydrogen Evolution Catalyst Studies: 30
6. Nickel Carbene CO2 Reduction Molecular Catalysts: 41
7. Metal-Organic Framework Thin Film Growth: 59
8. Metal-Organic Framework CO2 Reduction Catalysts: 70
9. Hybrid Inorganic-Biological CO¬2 Reduction Catalysts: 77
10. Conclusion: 85
11. References: 88

i
* Denotes equal contribution
Δ Publication central to dissertation

[1] "2-D Array Photonic Crystal Sensing Motif”, J. Zhang, L. Wang, J. Luo, A. Tikhonov, N.
Kornienko, and S.A. Asher, J. Am. Chem. Soc., 133, 9152 (2011).

[2] "Reflectivity Enhanced Two-Dimensional Dielectric Particle Array Monolayer Diffraction",
A. Tikhonov, N. Kornienko, J. Zhang, L. Wang and S.A. Asher, J. Nanophoton., 6, 063509
(2012).

Δ [3]"Visible Photoredox Catalysis: Selective Reduction of Carbon Dioxide to Carbon Monoxide
by a Nickel N-Heterocyclic Carbene Isoquinoline Complex”, V Thoi*, N. Kornienko*, C
Margarit, P. Yang and C. Chang, J. Am. Chem. Soc., 135, 14413 (2013).

Δ [4] “Mesoscopic Constructs of Ordered and Oriented Metal-Organic Frameworks on Plasmonic
Silver Nanocrystals” Y. Zhao*, N. Kornienko*, Z. Liu,C. Zhu, S. Asahina, T. Kuo, W. Bao, C.
Xie, O. Terasaki, P. Yang, O. Yaghi, J. Am. Chem. Soc., 137, 2199, 2015

Δ [5] “Solution Phase Synthesis of Indium Gallium Phosphide Alloy Nanowires” N. Kornienko,
D. Whitmore, Y. Yu, S. Leone and P. Yang, ACS Nano, 9, 3951 (2015)

Δ [6] “Operando Spectroscopic Analysis of an Amorphous Cobalt Sulfide Electrocatalyst” N.
Kornienko, J. Resasco, N. Becknell, C. Jiang, Y. Liu, K. Nie, X. Sun, J. Guo, S. Leone, P.
Yang, J. Am. Chem. Soc., 137, 7448 (2015)

[7] “Covalent Organic Frameworks Comprising Cobalt Porphyrins for Catalytic CO Reduction
2
in Water” S. Lin*, C. Dierks*, Y. Zhang*, N. Kornienko, E. Nichols, Y. Zhao, A. Paris, D.
Kim, P. Yang, O. Yaghi, C. Chang, Science, 349, 1208 (2015)

Δ [8] “Metal-Organic Frameworks for Electrocatalytic Reduction of Carbon Dioxide” N.
Kornienko*, Y. Zhao*, C. Kley, C. Zhu, D. Kim, S. Lin, C. Chang, O. Yaghi, P. Yang, J. Am.
Chem. Soc., 137, 14129 (2015)

ii
[9] “Atomically Thin Two-Dimensional Organic-Inorganic Hybrid Perovskites” L. Duo, A.
Wong, Y. Yu, M. Lai, N. Kornienko, S. Eaton, A. Fu, C. Bishak, J. Ma, T. Ding, N. Ginsberg,
L. Wang, A. Alivisatos, P. Yang, Science, 349, 6255 (2015)

[10] “Atomic Level Structure of P Ni Nanoframe Electrocatalysts by In-Situ X-Ray Absorption
3
Spectroscopy” N. Becknell, Y. Kang, C. Chen, J. Resasco, N. Kornienko, J. Guo, N. Markovic,
G. Somorjai, V. Stamenkovic, P. Yang, J. Am. Chem. Soc. 37, 15817 (2015)

[11] “Low-Temperature Solution-Phase Growth of Silicon and Silicon Containing Alloys” J.
Sun, F. Cui, C. Kiseilowski, Y. Yu, N. Kornienko, P. Yang, J. Phys. Chem. C. In Press - Online
DOI: 10.1021/acs.jpcc.5b08289

[12] “TiO /BiVO Nanowire Heterostructure Photoanodes Based on Type II Band Allignment” J.
2 4
Resasco, H. Zhang, N. Kornienko, N. Becknell, H. Lee, A. Briseno, J. Guo, P. Yang ACS
Central Science, 2, 80 (2016)

[13] “Single Nanowire Photoelectrochemistry” Y. Su*, C. Liu*, S. Brittman, J. Tang, A. Fu, N.
Kornienko, Q. Kong, P. Yang Nat. Nanotechnol. In Press

Δ [14] “Growth and Photoelectrochemical Energy Conversion of Wurtzite Indium Phosphide
Nanowire Arrays” N. Kornienko, N. Gibson, H. Zhang, S. Eaton, Y. Yu, S. Aloni, P. Yang ACS
Nano, In Press

[15] “Anisotropic Phase Segregation and Migration of Pt in Nanocrystals En Route to
Nanoframe Catalysts” Z. Niu, B. Becknell, Y. Yu, D. Kim, C. Chen, N. Kornienko, G.
Somorjai, P. Yang, Nat. Mater. Accepted

[16] “Synthesis and Composition Tunable Cesium Lead Halide Nanowires through Anion-
Exchange Reactions” D. Zhang, Y. Yang, Y. Bekenstein, Y. Yu, N. Gibson, A. Wong, S. Eaton,
N. Kornienko, Q. Kong, M. Lai, Y. Bekenstein, A. P. Alivisatos, S. R. Leone, P. Yang,
Submitted

[17] “Atomic Resolution Imaging of Halide Perovskites” Y. Yu, D. Zhang, C. Kisielowski, L.
Dou, N. Kornienko, Y. Bekenstein, A. P. Alivisatos, P. Yang, In Preparation

iii
Δ [18] “Spectroscopic Elucidation of Picosecond Energy Transfer Pathways in Hybrid Inorganic-
Biological Organisms for Solar-to-Chemical Production ” N. Kornienko*, K. Sakimoto*, D.
Herlihy, S. Nguyen, A. P. Alivisatos, C. B. Harris, A. Schwartzberg, P. Yang In Preparation

iv
2. Introduction
In the last few decades, a growing population combined with an increase in per capita energy
consumption has begun to deplete the finite fossil fuel sources currently used for power
generation1. The rapid depletion of fossil fuels and inherent harmful environmental effects
resulting from their usage is the impetus behind many recent efforts to develop alternative ways
to supply energy for mankind. Deemed the terawatt challenge, the search for alternative,
environmentally friendly technologies for solar energy conversion to provide the 20 terawatts
needed to sustain society’s current usage is of highest urgency and one of the main challenges
that society is currently facing2,3.
In contrast to fossil fuels such as coal and oil, alternative sustainable sources such as wind,
hydroelectric and solar power provide clean energy without the risk of depletion. In particular,
sunlight is among the most promising and abundant of these alternative energy sources - the total
amount of sunlight falling on earth’s surface, integrated over a year, equates to 23,000 terawatts4.
Efficiently harvesting a fraction of this total energy would be more than enough to sustainably
supply our growing society. Having realized this, significant research and development has been
applied to this area. Despite many decades’ worth of work and significant progress being made
in solar energy conversion, the fraction of society’s energy that results from the sun currently
amounts to less than 1%. Increasing this fraction will require collaborative efforts in the areas of
policy, engineering, and fundamental scientific research. Regarding the area of science and
engineering, improvements in cost and efficiency are essential to make solar energy a truly
viable alternative to fossil fuels.
Currently, photovoltaic (PV) cells are the main form of solar energy conversion, in which
electric power is generated upon the solar illumination of a semiconductor or organic light
absorbing material. While this is the currently most developed method to harness the sun’s
power, it has several drawbacks that render it incapable of being the sole source of solar power
generation. These drawbacks include the fact that electric power can only be generated when a
photovoltaic cell is under illumination and that society’s peak energy demand is in the evening
hours, when no sunlight is available. Hence, developing methods for solar energy harnessing and
storage is of paramount importance and an energy storage media in the form of fuels highly
desirable to be readily integrated into current infrastructures.
As complimentary approach to photovoltaics, photoelectrochemistry (PEC) employs solar
energy to drive chemical reactions for storing this energy in the form of chemical bonds5.
Inspired by natural photosynthesis, in which plants use sunlight to convert carbon dioxide into
sugars, PEC cells convert water or carbon dioxide into hydrogen or hydrocarbon fuels as an
energy dense storage media. This process accomplishes both solar energy absorption and
conversion in a single step. The resulting products can be directly used as nighttime energy
sources, transportation fuels, or as chemical feedstocks that are compatible with existing
infrastructures. Illustrated in figure 2.1, large scale implementation of PEC energy conversion
can help create a closed carbon cycle, in which CO emissions from vehicles and factories are
2
converted back into hydrocarbon fuels. To carry out these reactions, the semiconductor light
absorbers must generate sufficient voltage to efficiently drive the process as well as possess the
proper band alignments to make the reaction thermodynamically feasible. Furthermore, for this
process to be practical on a large scale, the materials must be earth abundant, have a catalytic
1
turnover frequency (TOF) matching the incident solar photon flux and be stable in their
operating reaction media.
The splitting of water into hydrogen and oxygen was first studied as a model system to
understand this process because of the simplicity of the reaction. The mechanism for both of the
half reactions of hydrogen evolution and oxygen evolution is now well understood and solar to
hydrogen efficiencies are steadily increasing.6-9. However, challenges of stability and cost
efficiency still need to be overcome and efficiencies need to be further improved. While
hydrogen is useful as a transportation fuel and chemical feedstock, additional desirable
hydrocarbon fuels such as methanol can be generated from the reduction of carbon dioxide.
Liquid hydrocarbons can be readily integrated into the current infrastructure and do not possess
the additional inherent challenge of gaseous storage. Carbon dioxide reduction, however,
implicates additional challenges that must be addressed in order to achieve similar efficiencies as
water splitting10. These challenges include the limited solubility of carbon dioxide in water, lack
of catalytic selectivity for a single reaction product, and the need for a high energy input to drive
the kinetically slower, multi-electron process. Moreover, carbon dioxide is a highly inert
molecule and the formation of multiple bonds to create complex molecules generally necessitates
much more energy than is thermodynamically required11. Ideally, CO reduction runs at room
2
temperature and atmospheric pressure employing visible solar light.
In the subsequent sections, I will illustrate my efforts towards the development of functional
PEC systems. Such systems can be viewed as modular, multi-component devices, where each
component can be improvised and re-integrated into a fully functional device. Within this
context, my work has focused on next-generation light absorber and catalyst design, synthesis,
investigation and utilization.

Figure 2.1. Photoelectrochemistry is a promising solution to generate fuels from renewable
energy.
2